Can you really rely on an app for contraception?

Hormonal contraception has come under scrutiny for causing side effects that affect mental health as well as physical health, with the result that some women are on the lookout for non-hormonal methods of contraception to avoid pregnancy. Currently, the only widely-used method of non-hormonal contraception (condoms aside) is the copper coil. Yet the coil, too, can cause some unwanted side effects, including heavier periods.

Having realised that women are seeking alternative non-hormonal contraception options, a new contraceptive app was launched this year, joining a handful of others. The difference? This one claims to be as reliable as condoms, to be almost as reliable as the pill, and has been classed in the same category as the condom. The app, Natural Cycles, uses an algorithm to calculate your fertile days — that is, the days you shouldn’t have sex if you don’t wish to get pregnant.

The algorithm works by calculating when you ovulate based on your body temperature, entered daily by you, which is said to rise by about 0.3 degrees on the day of ovulation before remaining elevated for the rest of the cycle. As an ovum only lives for roughly 24 hours, having unprotected sex after ovulation is unlikely to lead to pregnancy. A sperm can live for six days, however, meaning any sex between your period and ovulation may well lead to pregnancy. The app will display a ‘red’ day if it deems you are at risk of pregnancy, which means that you should use a condom or refrain from sex. The days when you can have unprotected sex and are unlikely to get pregnant show up green. If you don’t enter enough data for it to be certain, it shows up red as a precaution.

But can we really trust an app for contraception, given the huge fluctuations both in our own hormones and monthly cycles, and the huge fluctuations between different women? On top of that, can we really call it contraception if it is essentially just telling you when to abstain?

The app’s developers have marketed the app along with a big pile of scientific research that attempts to prove its effectiveness. In fact, inspection and certification organisation TÜV SÜD has approved Natural Cycles as a class IIb medical device to be used for contraception, putting it in the same category as the condom.

Using retrospective analysis, 4054 women used the app as contraception for a total of 2085 women-years — a unit of measurement that counts one year in the life of a woman who is sexually active and therefore at risk of pregnancy. Over 2053 women-years, there were 143 unplanned pregnancies, giving the app a Pearl Index (a commonly-used technique to measure the effectiveness of birth control) of 7.0 for typical use. When used perfectly, it has a Pearl Index of 0.5, meaning five out of 100 women will get pregnant.

Ten of the pregnancies in the typical use study were through fault of the app, falsely showing a “safe day” within the fertile window. Others were due to women ignoring the app and having unprotected sex on a red day. The app does, then, rely on a huge amount of responsibility from the user — and downsides identified by the study include the fact that it had a high dropout rate, and wasn’t conducted over a long enough period.

Despite the high success rate in preventing pregnancy when followed to the letter, contraception experts have spoken out about the risks associated with using fertility apps as a form of contraception, stating that while such apps can broaden the range of choices out there for women, the fact that they are classed as a medical device does not mean that they will effectively prevent pregnancy.

Dr Diana Mansour of the Faculty of Sexual and Reproductive Health (FSRH) at the Royal College of Obstetricians and Gynaecologists (RCOG), said that while there are many benefits to technology, there are also still big gaps. “I think that when you’re using any sort of app to look at your cycle, you need to know whether it has been evaluated,” she says. “We also know that for many people, the fertility awareness signs can vary, and there is a relatively high failure rate.”

On top of that, to really measure fertility you need to use a number of different components to provide data, including your cycle, your temperature, changes in your cycle, and more — and apps don’t always include all of these features. “Women do want choice,” adds Dr Mansour, “and we do know that women are looking for things where they can avoid hormones, but sometimes they may not be as effective as a barrier method.”

There is, of course, quite a bit of work required of someone who is using an app to avoid pregnancy. “It’s not just writing the day of your last period,” says Dr Mansour. “It’s a daily monitoring thing, you need to take your temperature before you get out of bed, before you even have anything to drink, and I think it does require an awful lot more attention on a daily basis than taking a pill, or having an implant, for example. It’s for those people who are really motivated.”

The temperature change that occurs after you ovulate is also so small that it cannot be detected with a regular thermometer. And Dr Mansour adds that the change can occur post-ovulation, by which time it is too late to protect against pregnancy. “You have to know what your pattern is over a few months so you can detect fertility from monitoring your regular cycle and temperature. Using your temperature alone is not going to be very effective. Ideally, you will have registered your cycle over three or four months as well as recording any changes in vaginal mucus.”

So can contraception apps really claim to be safe when they rely on so much information and depend on a body doing the same thing every month without fail? Natural Cycles were approached for comment, specifically on whether or not they should be marketing the app as contraception when it serves only to inform you when to abstain or use a method of contraception, and declined to respond. My question about whether or not they would recommend the app to women for whom it would be extremely problematic if they got pregnant was also met with silence.

“When people are using temperature as well as their menstrual cycle and physical changes, there is still a failure rate of 2-4 per cent when contraceptive apps are used in ideal conditions, and well over 15 per cent if they are not,” says Dr Mansour, talking about “contraceptive” apps in general, not just Natural Cycles. “So I think the failure rate is about nine per cent. When the pill is used perfectly the failure rate is less than one per cent. The pill is more effective at preventing pregnancy when used perfectly.”

So should women even be looking at using such an app at all, or are they best avoided for now? According to Dr Mansour, the app does give women more options and now there are many more tools out there that make recording your fertility easier. Yet there remains the problem of variability of the menstrual cycle and signs of ovulation, which leave it open to a higher failure rate. Ultimately, it is up to the person using the app, and whether the higher risk of pregnancy is going to prove to be that much of a problem. “If women are aware they are in a situation where it wouldn’t be a disaster to be pregnant, then it is very useful,” says Dr. Mansour. “But for someone for whom pregnancy would be a disaster, then they would be better off using a more effective method of contraception.”

Imogen Robinson

Deputy Editor, The Femedic

Imogen joined The Femedic after working as a news reporter. Becoming frustrated with the neverending clickbait, she jumped at the chance to work for a site whose ethos revolves around honesty and empathy. From reading articles by doctors to researching her own, and discussing health with a huge variety of women, she is fascinated by just how little we are told about our own bodies and women-specific health issues, and is excited to be working on a site which will dispel myths and taboos, and hopefully help a lot of women.